Self-cleaning flow restricting device

ABSTRACT

A continuous blow down having a plug-resistant flow restricting device and a pair of two-way valves so disposed in a single housing that the flow through the restricting device can be easily reversed to facilitate cleaning the restricting device while it is in service.

United States Patent [191 Dickinson [451 Feb. 19, 1974 SELF-CLEANINGFLOW RESTRICTING DEVICE Inventor: John 1). Dickinson, Swarthmore, Pa.

Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa.

Filed: Oct. 20, 1971 Appl. No.: 190,942

11.8. C1 137/546, 210/427, 137/599 Int. Cl. F16k 51/00 Field of Search210/411, 427, 423; 137/546,

References Cited UNITED STATES PATENTS I 12/1866 Hayes 210/427 137,6534/1873 Brown et a1. 210/427 Primary Examiner-Henry T. KlinksiekAttorney, Agent, or FirmF. .l. Baehr, Jr.

[5 7] ABSTRACT A continuous blow down having a plug-resistant flowrestricting device and a pair of two-way valves so disposed in a singlehousing that the flow through the restricting device can be easilyreversed to facilitate cleaning the restricting device while it is inservice.

4 Claims, 2 Drawing Figures 'PATENTEDFEBISISM A 3.792.719

FROM 2 BOILER GENERATOR LOAD F ow TE BOILER EE A R f HEATERSELF-CLEANING F LOW RESTRICTING DEVICE BACKGROUND OF THE INVENTION Thisinvention relates to steam turbines and more particularly to a positivedrain for the associated power plant piping and vessels, which must bedrained of water to prevent damage to the turbine due to wateraccumulating in the piping and flowing back into the turbine.

Certain extraction piping and feed water heater bleed piping from theturbine should be provided with positive drains, to prevent accumulationof water therein. If allowed to accumulate, the water may flow back intothe turbine, or flash due to a reduction of pressure resulting from arapid reduction or loss of load on the generator, and cause a slug ofwater to enter the turbine.v

Steam traps, which drain water from the piping are in use, however, theyare not 100 percent safe, as they become clogged by debris normallyfound in extraction and bleed piping.

Positive drains, such as an orifice or restriction are also utilized toprevent the build-up of water in the piping, however, they also becomeclogged, even when protected by strainers, which may themselves becomeplugged.

Large base load turbo-generators may be shut down as seldom as once ayear, therefore some type of positive drain which can be cleaned inservice is essential to positively prevent water from collecting in theextraction or bleed piping and to negate the possibility of slugsofwater being passed through the turbine and causing damage thereto.

SUMMARY OF THE INVENTION In general, a self-cleaning flow restriction,when made in accordance with this invention, comprises a flowrestricting device and a device for alternately reversing the flowthrough the flow restricting device.

BRIEF DESCRIPTION OF THE DRAWINGS The objects and advantages of thisinvention will become more apparent from reading the following detaileddescription in connection with the accompanying drawings, in which:

FIG. 1 is a flow diagram of a turbo-generator unit having aself-cleaning flow restricting device made in accordance with thisinvention disposed therein; and

FIG. 2 is an enlarged sectional view of the selfcleaning flowrestricting device.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings indetail, FIG. 1 shows a flow diagram of a turbo-generator 1, whereinmotive steam from a boiler (not shown) flows through a supply conduit 2and stop valve 3 to a turbine 4, and is exhausted to a condenser 5.Extraction or bleed steam is withdrawn from the motive steam throughextraction piping or conduit 7 to some intermediate stage of the turbineand to provide the steam for a feedwater heater 9, which heats thecondensate being returned to the boiler. A drain pipe or conduit 11 isdisposed between the extraction piping 7 and the condenser 5 andcontains a self-cleaning flow restricting device 13, which will bedescribed in detail hereinafter. Condensate collected in a hotwell 14 ofthe condenser 5 is pumped from the condenser to the feedwater heater 9by a condensate pump 15. The condensate then flows through the tubes ofthe feedwater heater 9 and is then picked up by a boiler feed pump 16and pumped to the boiler, where it is again converted to motive steam.

While the flow diagram only shows a single selfcleaning flow restrictingdevice 13, it is understood that a plurality of such devices would beutilized in an operational system.

As shown in FIG. 2, the self-cleaning flow restricting device 13comprises a duct 17 sized to restrict the flow therethrough to apredetermined amount and a plurality of apertures or ports 19 disposedat both ends of the duct 17, each aperture 19 having an open areasmaller than the open area of the duct 17, a pair of two-way valves 21and 22, disposed on each side of the duct 17 and a plurality ofpassageways or chambers 23, 24, 25, and 26, so disposed, that when thevalves 21 and 22 are set in one position, fluid flows through the duct17 in one direction, and when the valves 21 and 22 are set in anotherposition, fluid flows through the valve in the opposite directionblowing debris, which collected on the apertures 19, to the drain. Thepassageways and valves being arranged to allow the direction of flow tobe reversed without removing the restriction from service, and thusprovide for periodic flow reversals which blow debris collected on theapertures 19 to the drain, while the turbo-generator is operating.

The valves 21 and 22, as shown in FIG. 2, are hand operated, however,they could be adapted to operate automatically to reverse the directionof flow through the restriction periodically by utilizing electric,hydraulic or pneumatic operated drives to open and close the valves 21and 22, and appropriate means to automatically operate the drives sothat when one valve opens the other valve closes.

As shown in the drawing, the valves 21 and 22 and restricting duct 17are disposed in a rectangular shape casing or casting 29. The casing 29has an inlet duct or port 31 in communication with the conduit 7 and theinlet chamber 23, which is disposed lengthwise adjacent one wall 33 ofthe casing 29. An outlet duct or port 35 is disposed so as to be incommunication with the outlet chamber 24 and the drain conduit 11connecting the outlet port 35 to the condensor 5. The outlet chamber 24is disposed lengthwise adjacent a wall 39 parallel the one wall 33. Apair of intermediate chambers 25 and 26 are placed in communication bythe restricting duct 17 and are disposed between the inlet and outletchambers 23 and 24. Each intermediate chamber 25 or 26 has an inlet port41 and 42, respectively, and an outlet port 43 and 44, respectively,which place the intermediate chambers in communication with the inletchambers 23 and 24. Each inlet port 41 or 42 and outlet port 43 or 44has a valve seat 45 disposed on the intermediate chamber side thereofand a double seated valve plug 47 is adapted to plug the inlet port,when disposed in one position, and the outlet port, when disposed inanother position. The valve plugs 47 are each disposed on the end of avalve stem 49, which extends through the outlet port 43 or 44, the wall39, packing glands 50, and yokes 51. The outboard ends of the valvestems 49 have threads 53 which engage intemal threads 55 in the yokes51. The valve stems 49 have hand wheels 59 fastened thereto to providemanual operation of the valves 21 and 22.

A drip pot 6!) depends from the casing 29 and is in communication withthe inlet chamber 23 and is axially aligned with the inlet port 31 forcollecting large particles of debris being carried into the inletchamber 23 by fluid flowing therein. A blow down valve 61 closes thelower end of the dip pot 60 and may be opened to blow out debriscollected therein, while the turbogenerator is operating.

The self-cleaning restriction device as hereinbefore describedadvantageously provides a continuous drain, which can be periodicallycleaned, while in service to prevent clogging, and thereby eliminatewater pockets in the extraction or bleed piping, which couldinadvertentally flow back to the turbine or flash dueto a sudden drop inpressure resulting from a sudden drop or loss of load on the generatorand carry back slugs of water to the turbine, thus preventing water fromentering the turbine and causing damage thereto.

What is claimed is:

l. A self-cleaning flow restricting device comprising posed between saidinlet and outlet chambers and each intermediate chamber having one ofsaid inlet and outlet ports disposed therein placing said intermediatechambers in communication with said inlet and outlet chambers, and avalve plug so disposed within each intermediate chamber that when saidoutlet port in one intermediate chamber is plugged the associated inletport is open and vice versa; said first chamber having a drip potdepending therefrom for collecting large particles of debris; and flowrestricting means disposed between said intermediate chambers.

2. A self-cleaning flow restricting device as set forth in claim 1,wherein the drip pot has means disposed therein for blowing it downwhile in operation.

3. A self-cleaning flow restricting device as set forth in claim 1,wherein the drip pot has a blow down valve disposed on the lower endthereof.

4. A self-cleaning flow restricting device as set forth in claim 1,wherein the flow restricting means comprises a duct having an open areasufficiently small to restrict the flow to a predetermined amount and apluraiity of ports at both ends of the duct, each port having an openarea smaller than the open area of the duct.

1. A self-cleaning flow restricting device comprising an inlet chamberhaving an inlet duct and a pair of outlet ports having a valve seatdisposed in each of said ports and an outlet chamber having an outletduct and a pair of inlet ports having a valve seat disposed in each ofsaid inlet ports; a pair of intermediate chambers disposed between saidinlet and outlet chambers and each intermediate chamber having one ofsaid inlet and outlet ports disposed therein placing said intermediatechambers in communication with said inlet and outlet chambers, and avalve plug so disposed within each intermediate chamber that when saidoutlet port in one intermediate chamber is plugged the associated inletport is open and vice versa; said first chamber having a drip potdepending therefrom for collecting large particles of debris; and flowrestricting means disposed between said intermediate chambers.
 2. Aself-cleaning flow restricting device as set forth in claim 1, whereinthe drip pot has means disposed therein for blowing it down while inoperation.
 3. A self-cleaning flow restricting device as set forth inclaim 1, wherein the drip pot has a blow down valve disposed on thelower end thereof.
 4. A self-cleaning flow restricting device as setforth in claim 1, wherein the flow restricting means comprises a ducthaving an open area sufficiently small to restrict the flow to apredetermined amount and a plurality of ports at both ends of the duct,each port having an open area smaller than the open area of the duct.